Yael Mor

Research title
Elucidating the worm's connectome through light-induced expression of sex determination genes

Research project

The nematode Caenorhabditis elegans has two sexes- a great majority of self-fertilizing XX hermaphrodites and a minority (0.1%-0.2%) of X0 males. Males and hermaphrodites exhibit differential neuroanatomy: both have the same "core" nervous system composed of 294 neurons, while males and hermaphrodites have 89 and 8 sex specific neurons respectively.

In recent years, efforts have been made to characterize the neuronal and behavioral differences between males and hermaphrodites, and to decipher the genetic basis of those differences. Extensive research has revealed a complex network of effector genes and regulatory factors that determine the correct development for each sex and impact on the worms’ behavior. However, the exact developmental stages in which these factors are crucial for a coordinated sex-specific development are poorly determined.

To elucidate the genetic basis of sexual differences in a time-specific resolution, I will express at defined developmental windows two well-known genes from the sex determination pathway, fem-3 and her-1, in the nervous system. To facilitate this, I developed a novel light-induced method for spatiotemporal control of gene expression in C. elegans. The method combines the Q system (a system for binary gene expression), with two, well-known, light sensitive molecules- the cryptochrome circadian clock 2 (CRY-2) and the cryptochrome-interacting basic-helix-loop-helix 1 (CIB1), both first discovered in Arabidopsis thaliana.

I will be interested in identifying the critical periods for plasticity, at which it is possible to alter the nematode’s nervous system from a feminine to a masculine phenotype. In particular, I will test whether neurons may be generated de novo through genetic manipulation, and whether the changes in the nervous system could induce functional male specific behavior.